Picker machines are conventionally used to open or separate fibers from a fiber mat comprised of cotton, jute or the like. A typical picker machine comprises plural cylinders having a plurality of picker assemblies thereon, each of which has a multiplicity of picker teeth which strike and open the fiber mat. Rotation of the picker cylinder causes each picker tooth to contact the fiber mat once during each revolution of the cylinder. The picker teeth thereby open or separate the fibers of the mat.
In a typical picker machine installation, a feed roller advances stock toward a knife disposed between the feed roller and a picker cylinder. Rotation of the picker cylinder causes each picker tooth to strike the fiber stock once during each revolution of the cylinder. The teeth draw the stock across the knife and thereby sever portions of the stock. The severed portions are removed from the teeth for subsequent operations.
Among the known picker machines constructions, there is provided a cylinder having mounted in it a longitudinally extending picker bar having a T-slot therein, one leg of the T-slot opening through a side of the bar. The teeth each includes a working portion which is outside of the picker bar, and a base fitted in the slot, with a shank of the blade extending through the leg opening of the T-slot. Thus, the picker teeth have a profile of the base and shank which is of T-shape corresponding to the T-slot in the picker bar. The bases of the teeth are inserted into the T-slot from an end of the T-slot. The teeth were machined to close tolerances, to provide clearance between surfaces of the bases of the teeth and the corresponding surfaces of the picker bar to enable the teeth to be inserted into the picker bar. This resulted in substantial expenses in the manufacture of these teeth. The picker teeth are than held in position, as by an abutment which is secured in position against the end-most picker tooth base by a set screw or the like.
Barbod U.S. Pat. No. 3,445,895 provides a picker assembly which includes a picker bar with a T-slot, and a plurality of picker teeth having bases in the slot of the picker bar, a shank of the blade extending through the leg opening of the T-slot. The bases are configured so as to enable a base to be removed by turning it through approximately 90.degree., so as to permit it to be withdrawn from the picker bar through the leg opening of the T-slot, rather than requiring the removal of all of the teeth bases through the end of the picker bar. The bases of the teeth are provided with side surfaces which lie in planes perpendicular to the axis of the T-slot.
Scaife U.S. Pat. No. 663,583 discloses a cotton batting machine in which a picker bar with an open-sided beveled slot receives picker teeth having bases with inclined front and rear surfaces and a flat bottom surface to mate with the surfaces of the beveled slot: the side surfaces of these bases are perpendicular to the longitudinal axis of the beveled slot.
Frantz U.S. Pat. No. 449,438 discloses a thrashing cylinder with removable teeth which have bases with inclined side surfaces. Each tooth is inserted to an individual pocket of corresponding shape in the cylinder.
Fowler U.S. Pat. No. 2,429,157 discloses a pressure roll with removable wear segments, the teeth having configured bases and the cylinder having a number of individual pockets or notches into which the tooth base is inserted.
In the picker assemblies hereinabove described in which a picker bar has a longitudinally extending slot in which the bases of picker teeth are assembled in side-by-side relationship, the providing of tolerances and clearances, as hereinabove noted, has been required in order to enable the insertion of the teeth bases into the slot. This construction has necessarily resulted in some play or movement of the teeth bases in the picker bars, so that when the working portion of the picker teeth engage the work, forces are applied to the bases to move them in planes perpendicular to the axis of the picker cylinder, as permitted by the clearances and tolerances. The repetitive engagement of the picker teeth with the work causes repeated impacting of the teeth against the adjacent surfaces of the picker bar, causing rapid wear on the bases and picker bars, resulting in more frequent tooth breakage which, in turn, leads to increased expenses for replacement teeth and bars, the associated labor costs, and down time of the picker machine.
In recent years, a substantial increase in maintenance costs and replacement of picker teeth and picker bars have been observed, due to wear of the teeth and bars, and breakage of the teeth. It has been found that this accelerated wear has been caused, at least in part, because there has in recent time only been available raw material which is more difficult to "pick". For example, for many years burlap bagging, which had been discarded after use, was available as a major component of the raw material. Such bagging has been replaced to a substantial extent by plastic bagging, and accordingly discarded burlap bagging is now uncommon and cannot readily be acquired as the major raw material for the picking operations. As a consequence, other material, primarily bagging, is used, but at the present time, the discarded bagging which is available as a raw material is heavier and harder to chop or pick than the previously used burlap bagging.